An implantable medical device (IMD) is a medical device that is configured to be implanted within a patient anatomy and commonly employs one or more leads with electrodes that either receive or deliver voltage, current or other electromagnetic pulses from or to an organ or tissue for diagnostic or therapeutic purposes. In general, IMDs include a battery, electronic circuitry, a pulse generator, a transceiver and/or a microprocessor that is configured to handle communication with an external instrument as well as control patient therapy. The components of the IMD are hermetically sealed within a metal housing.
IMDs are generally programmed by, and exchange data with, external instruments controlled by physicians and/or the patient. Some commercially available external instruments use commercial operating systems (e.g., iOS, Android) that communicate through wireless bi-directional communication links with the IMDs. For example, mobile devices with Bluetooth Low Energy (BLE) circuitry are available for communication with certain implantable medical devices. The bi-direction communication links are formed using a wireless communication protocol that includes advertisement notices received by the external instruments. The advertisement notices are broadcast by the IMD at predetermined constant frequencies. The use of the advertising notices to facilitate the establishment of wireless communications involves a significant power consumption for the implanted medical device.
Currently, a strategy for connecting to a BLE enabled IMD is for the IMD to periodically advertise for a duration of the IMD life. Unfortunately, for IMDs with smaller batteries, the advertisement notices are spaced far apart over long advertisement intervals (e.g., minutes) in order to save battery life and extend longevity. In addition, it has been proposed, to use another external device such as a magnet to initiate a fast advertisement state in the IMD. The drawback of using a magnet is that the magnet introduces the inconvenience of having to carry extra external hardware. Also, a magnet can be used to change the behavior of the implantable device, and thus unintended consequences are possible.